基于R-L模型的参数识别快速方向元件

Quick Directional Element Based on R-L Model Parameter Identification

论述了基于R-L模型的参数识别方向保护原理,即通过求取系统参数R和L,利用内部和外部故障时系统参数R和L的符号关系来判断出故障的方向.该原理使用了基于R-L模型的解微分方程算法,因此不受非周期分量的影响.通过仿真比较R-L模型和分布参数模型的相频特性可知,该方法有很好的频带适用范围.针对无穷大电源系统中和经高阻接地时存在的电压灵敏度不足的问题,采用保护安装处的记忆电压代替其电压故障分量,从而使保护可以判别出故障的方向.经计算软件ATP仿真表明,该方法可以在5 ms甚至更短的时间内判断出故障的方向,使保护的动作速度和灵敏度都能得到很大提高.

A novel directional protection principle based on R-L model parameter identification is proposed, where the system resistance and inductance are sought out, then the symbolism of system resistance and inductance in interior and exterior faults is investigated to determine the fault direction. The corresponding method is immune from non-periodic component due to the essential dependence on the differential algorithm. The comparison of the phase-frequency characteristic between R-L model and distributed parameter model shows the applicable frequency band of this method. Considering the shortage of voltage sensitivity in small source impedance ratio systems and with high resistance earth fault, the voltage fault component is replaced by memory voltage component to determine the fault direction. ATP simulations show the method enables to determine the fault direction within 5 ms or even shorter period and enhance the rate and reliability of relay greatly.